Fetal brain-maternal aorta temperature differences in sheep ABRAMS, CFLENSHAW,

ROBERT, DONALD CATON, Luls B, &RET, CARLYLE LEON MANN, AND DONALD H. BARRON. Fetal brainmaternal aorta tm~erature d@erences in sheep. Am. J, Physiol. 2 17(6) : I6 194622, I969.-Thermocouples were implanted chronically in the fetal brain and maternal aorta respectively of 1 I pregnant Dorset and Columbian ewes, at stages between the 122nd and 139th days of gestation. In six apparently unstressed ewes, with good appetites, that carried fetuses seen dr felt to move actively in utero and found to be alive at delivery, the fetal brain temperature was 0.4-0.8 C higher than the maternal blood. This temperature difference increased in some animals shortly before they delivered, The fetal brain temperature remained higher than that of the maternal blood during a fever induced by the injection of a pyrogen into the ewe. Death of the fetus in utero, judged by the absence of fetal activity and established by its subsequent delivery dead, appeared to be correlated with a change in the record of the temperature difference which included its reversal during normal oscillations in the temperature of the maternal blood,